Application of Different Image Processing Techniques on Aster and ETM + Images for Exploration of Hydrothermal Alteration Associated with Copper Mineralizations Mapping Kehdolan Area ( Eastern Azarbaijan Province-Iran )

The Kehdolan area is located at 20 kilometers to the south-east of Dozdozan Town (Eastern Azarbaijan Province). According to structural geology, volconic rocks are situated in Alborz-Azarbyjan zone, and faults are observed in the same direction to this system with SE-NW trend. The results show that kaolinite alteration trend with Argilic and propylitic veins is the same direction with SW-NE faults in this area. Therefore, these faults with these trends can be considered as the mineralization control for determination of the alterations. Different image processing techniques, such as false color composite (FCC), band ratios, color ratio composite (CRC), principal component analysis (PCA), Crosta technique, supervised spectral angle mapping (SAM), are used for identification of the alteration zones associated with copper mineralization. In this project ASTER data are process and spectral analysis to fit for recognizing intensity and kind of argillic, propylitic, philic, and ETM+ data which are process and to fit for iron oxide and relation to metal mineralization of the area. For recognizing different alterations of the study area, some chemical and mineralogical analysis data from the samples showed that ASTER data and ETM+ data were capable of hydrothermal alteration mapping with copper mineralization. Copper mineralization in the region is in agreement with argillic alteration. SW-NE trending faults controlled the minerali-


Introduction
ASTER satellite data processing for mineralization mapping was used to detect alteration and detect mineral exploration targets [1] [2].ASTER is the Advanced Spaceborne Thermal Emission and Reflection Radiometer, a multi-spectral sensor onboard one of NASA's Earth Observing System satellites, Terra, which was launched in 1999.ASTER sensors measure reflected and emitted electromagnetic radiation from earth's surface and atmosphere in 14 channels (or bands).There are three groups of channels: three recording visible and near infrared radiation (VNIR) at a spatial resolution of 15 m; six recording portions of shortwave infrared radiation (SWIR) at a spatial resolution of 30 m; and five recording thermal infrared radiation (TIR) at a resolution of 90 m.The higher spectral resolution of ASTER (compared to Landsat, for example-Figure 1) especially in the shortwave infrared region of the electromagnetic spectrum makes it possible to identify minerals and mineral groups such as clays, carbonates, silica, iron-oxides and other silicates.An additional backward-looking band in the VNIR makes it possible to construct digital elevation models from bands 3 and 3b.ASTER swath width is 60 km (each scene is 60 × 60 km) which makes it useful for regional mapping [3].
There are a few things to note when using ASTER imagery for regional mineralogical mapping.Firstly, cloud cover, vegetation and atmospheric effects can severely mask or alter surface signals in this project ASTER, ETM+ data to correct with log residuals calibration method at ENVI 5/1 software [4] [5].Secondly, bands and band ratios do not indicate the occurrence of a mineral with absolute certainty or with any idea of quantity, so this step is essential on ground truth and set appropriate thresholds.Thirdly, every terrain is different, so ratios which work in some areas for a particular mineral or assemblage may not show the same thing elsewhere.As a result of these factors, it is important not to look at ASTER images in isolation from other data.If possible, datasets such as geology and structural maps, geochemistry, PIMA analyses (ground truthing), radiometrics, and any other available data should be used in conjunction with ASTER for best results [6] [7].Several methods have been conducted for recognizing different alterations with ASTER data.Different image processing techniques such as false color composite, band ratios, color ratio composite, principal component analysis, Crosta technique, supervised spectral angle mapping, and neural network classification are used for identification of the alteration zones associated with copper mineralization.The principal component analysis (PCA), Crosta technique, and supervised spectral angle mapping (SAM) method seem to be equally applicable to all cases for detecting alteration zone and minerals.In this study, concentration-area, Crosta technique, and supervised spectral angle mapping method were used [6] [8].

Concentration-Area
In recent years, application of remote sensing in mineral exploration had been developed and becoming an important tool.Most important capability of satellites in mining exploration is recognizing altered area.Because of close spatial relationship between mineral deposits and alteration, mineral mapping based of satellite data accelerate the exploration and reduce the cost [8].
The principal component analysis (PCA), Crosta technique to know by person in 1901, in 1933 Helting suggested to calculate method [9] [10].The target enter variable p of X 1 ... X p , and know compound of p for component Z 1 ... Z p , do not correlation [9] [11]- [15].Classification supervised spectral angle mapping (SAM) need to ROI educationa file.SAM method by reason angel pixel to fabricate in N dimention with coordinates axise [16] [17].

Geological Setting of the Case Studies
The Studies area is located at 20 kilometers south-east of Dozdozan Town (Eastern Azarbaijan Province).According to structural geology, volconic rocks are situated in Alborz-Azarbyjan zone, and faults observe in same direction to this system with SE-NW trend that these are cut off with new faults with SW-NE trend.The results show that kaolinite alteration trend with Argilic and propylitic veins are same direction with SW-NE faults in this area.
Therefore, these faults with these trends can be considered as the mineralization control for determination of the alterations.Oldest rock types in the area are Eocene Andesit-Basalt.

Conclusion
Investigation shows that ETM+ data due to its blue region spectral band can enhance the iron oxide rich areas much better than ASTER data.ASTER data due to its various spectral bands in the short wave infrared are more capable of enhancing clay bearing areas.The results showed that Crosta technique, supervised spectral angle mapping better method for enhancing alteration at ASTER data.Results obtained by study on Kehdolan area indicate the potential use of the ASTER data to fit for kind alteration of argillic, propylitic, philic, and ETM+ data are to fit for the iron oxide and relation to metal mineralization of the area.The study area Argilic alteration expands that relationship with mineralization copper which is the same direction with SW-NE faults in this area and relationship with Oligocene Syenit dyke unit as in central parts of the study.Result study for control with geological particulars, showed more probable anomaly distribution copper mineralization.

Figure 1 .
Figure 1.Distribution of ASTER and Landsat channels with respect to the electromagnetic spectrum.

Figure 16 .
Figure 16.The coordinates of sampling points.

Table 8 .
Heavy mineral sample of Kehdolan area.